Defensive publication

ABSTRACT

WET-PROCESS PHOSPHORIC ACIDS CONTAIN METALLIC IMPURITIES-MOSTLY MAGNESIUM, ALUMINUM, AND IRON-DISSOLVED IN THE ACIDULATION OF THE PARENT PHOSPHATE ROCK. AMMONIUM POLYPHOSPHATE FERTILIZER SOLUTIONS PREPARED THEREFROM DEPOSIT SLUDGES OF PHOSPHATES OF THE METALLIC IMPURITIES THAT INTERFERE SERIOUSLY WITH MECHANICAL HANDLING OF THE LIQUIDS. FORMATION OF THE SLUDGES CAN BE PREVENTED, HOWEVER, BY ADDITION OF FLUORINE AS EITHER FLUORIDE OR FLUOSILICATE. A MINOR EXCESS OF FLUORIDE OVER THAT REQUIRED TO FORM THE MOST COMMON SLUDGE PHASE, WATER-INSOLUBLE SALT   MGAL(NH4)6(P2O7)2F2 6H2O   IN AMMONIUM AND POTASSIUM POLYPHOSPHATE LIQUID FERTILIZER SOLUTIONS PREVENTS THE PRECIPITATION OF THESE METALLIC IMPURITIES. THE PRECIPITATION OF LESS COMMON SOLID PHASES SUCH AS MG(NH4)IP2O7 4H2O,   AL(NH4)2P2O7OH 3H2O AND MG(NH4)6(P2O7)2 6H2O   IS PREVENTED WHEN THE FLUORIDE CONCENTRATION IS INCREASED TO GIVE A SEQUESTRATION RATIO (S.R.) OF ABOUT 0.5 AT A 50% POLYPHOSPHATE CONTENT OR 0.14 AT A POLYPHOSPHATE VALUE OF 10% OF THE TOTAL P2O6, SAID SEQUESTRATION RATION BEING DETERMINED BY THE EMPIRICAL EQUATION:   WT. PERCENT F   S.R.-WT. PERCENT MGO + 3WT. PERCENT AL2O2 + 0.33 WT. PERCENT FE2OSP@ EFFECTIVELY, THIS INCREASE IN FLUORIDE CONTENT SHIFTS THE SOLUTION COMPOSITION FROM A REGION OF STABILITY FOR THESE INSOLUBLE SALTS TO A REGION WHERE WATER-SOLUBLE COMPOUNDS, SUCH AS DIMORPH 11 OF MGAL(NH4)5(P2O7)2F2 6H2O, ARE THE STABLE PHASES, THUS SEQUESTERING THE METALLIC CATIONS.

DFENSWE ULiCATlUN UNITED STATES PATENT OFFICE Published at the requestof the applicant or owner in accordance with the Notice of Dec. 16.1969, 869 O.G. 687. The abstracts of Defensive Publication applicationsare identified by distinctly numbered series and are arrangedchronologically. 'lhe heading of each abstract indicates the number ofpages of specification, including: claims and sheets of drawingscontained in the application as originally filed. The files of theseapplications are available to the public for inspection and reproductionmay be purchased for 30 cents a sheet.

Defensive Publication applications have not been examined as to themerits of alleged invention. The Patent Ofiice makes no assertion as tothe novelty of the disclosed subject matter.

PUBLISHED SEPTEMBER 2i, 1971 STABiLIZATION 0F PQLYPHOSPHATE FERTIL- IZERSOLUTEONS BY FLUORIDES 0R FLUO- SILICATES Alva W. Frazier, 2219 RandolphSt, Florence, Ala. 35630 Continuation-impart of application Ser. No.30,264, Apr. 20, 1970. This application Oct. 21, 1970, Ser. No. 82,809

int. Cl. C05b 7/00, 13/06 US. Cl. 71-34 No Drawing. 2?. PagesSpecification Wet-process phosphoric acids contain metallicimpurities-mostly magnesium, aluminum, and iron-dissolved in theacidulation of the parent phosphate rock. Ammonium polyphosphatefertilizer solutions prepared therefrom deposit sludges of phosphates ofthe metallic impurities that interfere seriously With mechanicalhandling of the liquids. Formation of the sludges can be prevented,however, by addition of fluorine as either fluoride or fluosilicate.

A minor excess of fluoride over that required to form the most commonsludge phase, water-insoluble salt in ammonium and potassiumpolyphosphate liquid fertilizer solutions prevents the precipitation ofthese metallic impurities. The precipitation of less common solid phasessuch as Mg(NH P O -4H O,

is prevented when the fluoride concentration is increased to give asequestration ratio (S.R.) of about 0.5 at a 50% polyphosphate contentor 0.14 at a polyphosphate value of 10% of the total P 0 saidsequestration ratio being determined by the empirical equation:

Wt. percent F Wt. percent MgO 3 Wt. percent A1 0 0.33 wt. percent. Fc dEiiectively, this increase in fluoride content shifts the solutioncomposition from a region of stability for these insoluble salts to aregion Where Water-soluble compounds, such as dimorph ll of MgAl(NH (P OF -6H O, are the stable phases, thus sequestering the metallic cations.

